import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../core/cache/cached.dart';
import '../../core/widgets/stale_banner.dart';
import 'allocation_tab.dart';
import 'benchmarks_card.dart';
import 'holdings_tab.dart';
import 'providers.dart';
import 'scope_selector.dart';

/// Портфель: позиции и аллокация as two tabs of one screen, sharing one scope.
///
/// They are tabs rather than two navigation destinations because they answer two halves of
/// the same question, and because a tenth item in the bottom bar would leave 40 px per
/// label on a phone.
///
/// One offline banner covers both tabs (`docs/ai/offline-cache.md`) — `TabBarView` builds
/// both eagerly anyway, so watching every provider here to compute it costs nothing extra.
class PortfolioPage extends ConsumerWidget {
  const PortfolioPage({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final stale = oldestFetch([
      ref.watch(portfolioSummaryProvider).valueOrNull?.fetchedAt,
      ref.watch(holdingsProvider).valueOrNull?.fetchedAt,
      ref.watch(valueSeriesProvider).valueOrNull?.fetchedAt,
      ref.watch(portfolioReturnsProvider).valueOrNull?.fetchedAt,
      ref.watch(benchmarkRowsProvider).valueOrNull?.fetchedAt,
      ref.watch(allocationProvider).valueOrNull?.fetchedAt,
    ]);

    return DefaultTabController(
      length: 2,
      child: Scaffold(
        appBar: AppBar(
          title: const Text('Портфель'),
          actions: const [ScopeSelector(), SizedBox(width: 8)],
          bottom: const TabBar(
            tabs: [
              Tab(text: 'Позиции'),
              Tab(text: 'Аллокация'),
            ],
          ),
        ),
        body: Column(
          children: [
            if (stale != null)
              Padding(
                padding: const EdgeInsets.fromLTRB(16, 12, 16, 0),
                child: StaleBanner(fetchedAt: stale),
              ),
            const Expanded(
              child: TabBarView(
                children: [
                  HoldingsTab(sections: HoldingsSections.table),
                  AllocationTab(),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}